Method of producing rimmed steel ingots



Patented July 2, 1940 UNITED STATES PATENT OFFICE METHOD or raonocmommmzn STEEL moors James W. Kinnear, Pittsburgh, Pa.

No Drawing." Application October 7, 1939,

Serial No., 298,505

4 Claims. (once-20o) inches will not rim properly because the ferrostatic pressure prevents proper gas evolution during the rimming period. The best quality 'of rimmed steel ingots are produced when the ingots are about 65 inches long, the ferrostatic pressure in this instance being insuflicient to prevent acfive gas evolution and, hence, good rimming ac- [5 Obviously, ingots of such short lengths, as contrasted to ingots of non-effervescent steel of from 90 to lltl inches in length, require the use of an objectionably larger number of molds, stools, ingot cars, pouring platforms and stripping facilities during their: casting. Furthermore, the production of the soaking pits and slab mills is very considerably reduced when handling such short ingots. Another objectionable feature is that, due to their short lengths, the ingot to slab yield suitable for quality products in the case of ordinaryrimmed steel ingots, is undesirably low.

All of these objectionable features would be eliminated if rimmed steel ingots' could be produced in lengths comparable to or longer than it is usual to make ingots of non-efiervescent steel.

According to the present invention, eifervescent or rimming steelis cast into an ingot mold to a height not greater than will permit proper rimming action of the steel or, in other words, to a height not exceeding 75 inches. ,Better results are obtained it the steel is cast to a height of about 65 inches. This steel is then allowed to ,stand in the mold while rimming proceeds to the desired degree. That is to say, the steel stands until it rims sufliciently to provide the ingot skin desired. v a 7 At this point, conventional procedure is to either cap the steel or place a plate on its'top, although sometimes the steel is simply allowed to stand until it solidifies 'sufliciently for stripingot. Also, here again, the steel should not be cast to a height greater than about 75 inches.

This additional steel is cast into the mold as soon as possible after the steel initially cast has rimmed to the extent desiredand while the in- 5 terior portion of this initially cast steel is still molten. As the additionally cast steel effervesces, there being little or no effervescense from the initially cast steel at this time, metalloids and some solidified'metal are picked up by 10 this additionally cast steel from the surface of the initially cast steel. Due to therimming action of the additionally cast steel; the metalloids thus picked up are well distributed, any solidified metal being, of course, melted by the additional steel.

If the subsequently cast or additional steel is of the same composition as the initially cast steel, it is possible, by controllingits rimming to obtain an ingot skin comparable to that of the steel initially cast, to produce a long, single rimmed steel ingot having at least approximately the same ingot structure throughout.

It is to be understood that ingot molds must be used which are of suitable lengths, it being obfviously impossible to use the short molds usually used in the casting of rimming steel. Upon strip- Due to their lengths, it' is possible to obtain higher yields of metal which can be rolled into products of the highest quality. During casting, a smaller number of molds, stools, etc., are required than in the case of the production of ordinary, rimmed steel ingots. Obviously, economies are effected throughout, while, in addition, the steel produced has actually been found to be superior to even the good portions of conventionally rimmed steel ingots.

Although the invention has been described as producing double-length ingots, it is obvious that any length ingot may be produced, the length depending, of course, on the equipment available for the working of the ingot. In any event, the last metal cast can be finished by conventional methods such as by capping or placing a plate on its top. if these practices are desirable.

I claim: 4

1. A method of producing a rimmed steel ingot, including casting rimming steel into an ingot mold to a height not greater than permit proper'rimmingaction of the steel, allowing the steel to stand until it rims sufliciently to provide the ingot skin desired and then casting additional proper rimming action of the steel, allowing the steel to stand until it rims sufilciently to provide the ingot skin desired and then casting additional steel into the mold on top of the rimmed steel to a height not greater than will permit proper rimming action of the additional steel, the moldbeing sufiiciently long to accommodate the additional steel, all of the steel being of the same composition and rimming of the additional steel being controlled to produce an ingot skin comparable to that of the steel initially cast so as to produce along, single ingot having at least approximately the sameingot structure throughout. a

3. A method of producing arimmed steel ingot, including casting rimming steel into an ingot mold to a height not greater than will permit proper rimming action of the steel, allowing the steel to stand until it rims sumciently to provide the ingot skin desired and then casting additional steel into the mold on top of the rimmed steel to a height not greater than will permit proper rimming action of the additional steel, the mold being sufliciently long to accommodate the additional steel and the additional steel being cast while the interior of the initially cast steel is still molten. i

4. A method of producing a rimmed steel ingot, including casting rimming steel into an in-' got mold to a height not greater than will permit proper rimming action of the steel, allowing the steel to stand until it rims suificiently to provide the ingot skin desired and then casting additional steel into the mold on top of the rimmed steel to a height not greater than will permit proper rimming action of the additional steel, the mold being sufliciently long to accommodate the additional steel ,and the additional steel being cast while the interior of the initially cast steel is still molten, all of the steel being of the same composition and rimming of the additional steel being controlled to produce an ingot skin comparable to that of the steel initially cast so as to produce a long, single ingot having at least approximately the same ingot structure throughout.

JAMES W. KINNEAR. 

